Your wingpower. Not so much to know what yours is, but to try and figure out how the scale works. I’m guessing it is something like a LOG scale based on how much Fluttershy was able to improve, but I really don’t know.

Your wingboner of course.

The depth of your… uh, perception. Yes. Depth perception is very important at the speeds you fly…
 
liarjackface.jpg

yes, that’s exactly what I want to measure RD  
Your “wat” level

Wingspan
 
Don’t worry, its quite generous for a young pegasus your age
 
Surely you won’t have your wings measured in front of your peers with some pegajocks laughing at you and having to try to look tough ESPECIALLY in front of that ‘dark but deep’ girl who claims her adopted parents are griffons but you put up with her because she is pretty wryly intelligent and has similar nerdy interests but DEAR LUNA she is SO pretty and out of your league and that bucking pegasus stallion with the douchey black mane that goes over one eye and plays the guitar and talks about ‘oh yeah I’m totally getting into the Lunar Guard when I grow up’ is ALL over her why do girls even like that douchebag!?
 
…
 
…Uh yeah cough

Your hoof length. I know you have a thing about your feet, but it’s needed for the horseshoes.

Your weight. I need to know if I can carry you.

Your ego, that thing must be bigger than canterlot!

Your lock of hair.